Mixing bleed and ram air using an air cycle machine with two turbines

ABSTRACT

An air cycle machine for an environmental control system for an aircraft is provided. The air cycle machine includes a compressor configured to compress a first medium, a turbine configured to receive second medium, a mixing point downstream of the compressor and downstream of the turbine; and a shaft mechanically coupling the compressor and the turbine.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. patent application Ser. No.15/604,496, filed May 24, 2017 which claims benefit of priority to U.S.Provisional Application No. 62/341,887, filed May 26, 2016, thedisclosure of which is incorporated herein by reference in its entirety

BACKGROUND

In general, contemporary air condition systems are supplied a pressureat cruise that is approximately 30 psig to 35 psig. The trend in theaerospace industry today is towards systems with higher efficiency. Oneapproach to improve airplane efficiency is to eliminate the bleed airentirely and use electrical power to compress outside air. A secondapproach is to use lower engine pressure. The third approach is to usethe energy in the bleed air to compress outside air and bring it intothe cabin.

BRIEF DESCRIPTION

According to one or more embodiments, an air cycle machine for anenvironmental control system for an aircraft is provided. The air cyclemachine includes a compressor configured to compress a first medium; aturbine configured to receive second medium; a mixing point downstreamof the compressor and downstream of the turbine; and a shaftmechanically coupling the compressor and the turbine.

According to one or more embodiments or the above air cycle machineembodiment, the air cycle machine can comprise a fan on the shaft.

According to one or more embodiments or any of the above air cyclemachine embodiments, the fan can be located at a first end of the shaft.

According to one or more embodiments or any of the above air cyclemachine embodiments, the air cycle machine can comprise a second turbinemounted on the shaft and can be configured to expand the first medium.

According to one or more embodiments or any of the above air cyclemachine embodiments, the turbine can be located at the first end of theshaft.

According to one or more embodiments or any of the above air cyclemachine embodiments, the air cycle machine can comprise a fan on theshaft, and the fan can be located at a second end of the shaft.

According to one or more embodiments or any of the above air cyclemachine embodiments, the second turbine can be configured to receive athird medium, and the third medium can be cabin discharge air.

According to one or more embodiments or any of the above air cyclemachine embodiments, the first medium can comprise fresh air, and thesecond medium can comprise bleed air.

According to one or more embodiments, an air conditioning system for anaircraft is provided. The air conditioning system comprises a compressorconfigured to compress a first medium; a turbine configured to receive asecond medium; a mixing point downstream of the compressor anddownstream of the turbine; and a shaft mechanically coupling thecompressor and the turbine.

According to one or more embodiments or the above air conditioningsystem embodiment, the air conditioning system can comprise a secondturbine mounted on the shaft and configured to expand the first medium.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a fan driven by a third turbine driven by the second medium.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise an integral rotor comprising the third turbine and the fan.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a second shaft mechanically coupling the fan and the thirdturbine.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a fan driven by a motor.

According to one or more embodiments or any of the above airconditioning system embodiments, the second turbine can be configured toreceive a third medium, and wherein the third medium is cabin dischargeair.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a second turbine configured to expand the first medium to drivea fan.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise an integral rotor comprising the second turbine and the fan.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a third turbine mounted on the shaft and configure to receivecabin discharge air.

According to one or more embodiments or any of the above airconditioning system embodiments, the air conditioning system cancomprise a second shaft mechanically coupling the fan and the secondturbine.

According to one or more embodiments or any of the above airconditioning system embodiments, the second turbine can be configured toreceive a third medium, and the third medium can be cabin discharge air.

Additional features and advantages are realized through the techniquesof the embodiments herein. Other embodiments are described in detailherein and are considered a part of the claims. For a betterunderstanding of the embodiments with the advantages and the features,refer to the description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter is particularly pointed out and distinctly claimed inthe claims at the conclusion of the specification. The forgoing andother features, and advantages thereof are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 is a diagram of an schematic of an environmental control systemaccording to an embodiment;

FIG. 2 is operation example of an environmental control system thatmixes fresh air with bleed air according to an embodiment;

FIG. 3 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes a bleed air driven fan, according to an embodiment;

FIG. 4 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes an electrically driven fan, according to an embodiment;

FIG. 5 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes a fresh air driven fan, according to an embodiment;

FIG. 6 is operation example of an environmental control system thatmixes fresh air with bleed air according to another embodiment;

FIG. 7 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes a bleed air driven fan, according to another embodiment;

FIG. 8 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes an electrically driven fan, according to another embodiment;

FIG. 9 is operation example of an environmental control system thatmixes fresh air with bleed air, where the environmental control systemincludes a fresh air driven fan, according to another embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the FIGS.

Embodiments herein provide an environmental control system of anaircraft that mixes mediums from different sources and uses thedifferent energy sources to power the environmental control system andto provide cabin pressurization and cooling at a high fuel burnefficiency. The medium can generally be air, while other examplesinclude gases, liquids, fluidized solids, or slurries.

Turning to FIG. 1, a system 100 that receives a medium from an inlet 101and provides a conditioned form of the medium to a chamber 102 isillustrated. The system 100 comprises a compressing device 110. Asshown, the compressing device 110 comprises a compressor 112, a turbine113, a fan 116, and a shaft 118. The system 100 also comprises a primaryheat exchanger 120, a secondary heat exchanger 130, a condenser 160, awater extractor 162, and a reheater 164.

The compressing device 110 is a mechanical device that includescomponents for performing thermodynamic work on the medium (e.g.,extracts work from or works on the medium by raising and/or loweringpressure and by raising and/or lowering temperature). Examples of thecompressing device 110 include an air cycle machine, a three-wheel aircycle machine, a four-wheel air cycle machine, etc.

The compressor 112 is a mechanical device that raises the pressure ofthe medium received from the inlet 101. Examples of compressor typesinclude centrifugal, diagonal or mixed-flow, axial-flow, reciprocating,ionic liquid piston, rotary screw, rotary vane, scroll, diaphragm, airbubble, etc. Further, compressors can be driven by a motor or the mediumvia the turbine 113.

The turbine 113 is mechanical device that drives the compressor 112 andthe fan 116 via the shaft 118. The fan 116 (e.g., a ram air fan) is amechanical device that can force via push or pull methods air throughthe shell 119 across the heat exchangers 120 and 130 at a variable flowrate to control temperatures. The shell 119 receives and directs amedium (such as ram air) through the system 100. In general, ram air isoutside air used as a heat sink by the system 100.

The heat exchangers 120 and 130 are devices built for efficient heattransfer from one medium to another. Examples of heat exchangers includedouble pipe, shell and tube, plate, plate and shell, adiabatic wheel,plate fin, pillow plate, and fluid heat exchangers.

The condenser 160 and the reheater 164 are particular types of heatexchangers. The water extractor 162 is a mechanical device that performsa process of taking water from the medium. Together, the condenser 160,the water extractor 162, and/or the reheater 164 can combine to be ahigh pressure water separator.

The elements of the system 100 are connected via valves, tubes, pipes,and the like. Valves (e.g., flow regulation device or mass flow valve)are devices that regulate, direct, and/or control a flow of a medium byopening, closing, or partially obstructing various passageways withinthe tubes, pipes, etc. of the system 100. Valves can be operated byactuators, such that flow rates of the medium in any portion of thesystem 100 can be regulated to a desired value.

As shown in FIG. 1, the medium can flow from an inlet 101 through thesystem 100 to a chamber 102, as indicated by solid-lined arrows. A valeV1 (e.g., a mass flow control valve) controls the flow of the mediumfrom the inlet 101 to the system 100. Further, a vale V2 controlswhether the flow of the medium from the secondary heat exchanger 130bypasses the condenser 160 in accordance with a mode of the system 100.A combination of components of the system 100 can be referred to as anair conditioning pack or a pack. The pack can begin at a vale V1 andconclude as air exits the condenser 162.

The system 100 will now be described in view of the above aircraftembodiment. In the aircraft embodiment, the medium can be air and thesystem 100 can be an environmental control system. The air supplied tothe environmental control system at the inlet 101 can be said to be“bled” from a turbine engine or an auxiliary power unit. When the air isbeing provided by the turbine engine or the auxiliary power unitconnected to the environmental control system, such as from the inlet101, the air can be referred to as bleed air (e.g., pressurized air thatcomes from an engine or an auxiliary power unit). The temperature,humidity, and pressure of the bleed air vary widely depending upon acompressor stage and a revolutions per minute of the turbine engine.

Turning now to FIG. 2, a schematic of an environmental control system200 (e.g., an embodiment of system 100), as it could be installed on anaircraft, where in operation the environmental control system 200 mixesfresh air with bleed air, is depicted according to an embodiment.Components of the system 100 that are similar to the environmentalcontrol system 200 have been reused for ease of explanation, by usingthe same identifiers, and are not re-introduced. Alternative componentsof the environmental control system 200 include a compressing device 210(that comprises a compressor 212, a turbine 213, a turbine 214, a fan116, and a shaft 118), an inlet 201, an outlet 202, an outflow valveheat exchanger 230, a water collector 271, and a water collector 272,along with a path for the medium denoted by the dot-dashed line F2(where the medium can be provided from the chamber 102 into theenvironmental control system 200).

In view of the above aircraft embodiment, when a medium is beingprovided from the chamber 102 (e.g., air leaving a pressurized volume,cabin of the aircraft, or cabin and flight deck of the aircraft), themedium can be referred as chamber discharge air (also known as pressuredair or cabin discharge air). Note that in one or more embodiments, anexhaust from the environmental control system 200 can be released toambient air through the shell 119 or sent to the outlet 202 (e.g., acabin pressure control system).

Further, when a medium is being provided from the inlet 201, the mediumcan be referred to as fresh outside air (also known as fresh air oroutside air destined to enter the pressurized volume or chamber 102).The fresh outside air can be procured by one or more scoopingmechanisms, such as an impact scoop or a flush scoop. Thus, the inlet201 can be considered a fresh air inlet.

In low altitude operation of the environmental control system 200,high-pressure high-temperature air from either the turbine engine or theauxiliary power unit via inlet 101 through the valve V1 enters theprimary heat exchanger 120. The primary heat exchanger 120 cools thepressure high-temperature air to nearly ambient temperature to producecool high pressure air. This cool high pressure air enters the condenser160, where it is further cooled by air from the turbines 213 and 214 ofthe compressing device 210. Upon exiting the condenser 160, the coolhigh pressure air enters the water extractor 272 so that moisture in theair is removed.

The cool high pressure air enters the turbine 213 through a nozzle. Thecool high pressure air is expanded across the turbine 213 and workextracted from the cool high pressure air. This extracted work drivesthe compressor 212 used to compress fresh outside air. This extractedwork also drives the fan 216, which is used to move air through theprimary heat exchanger 120 and the secondary heat exchanger 130 (alsoknown as ram air heat exchangers).

The act of compressing the fresh outside air, heats the fresh outsideair. The compressed fresh outside air enters the outflow valve heatexchanger 230 and is cooled by the chamber discharge air to producecooled compressed fresh outside air. The cooled compressed fresh outsideair then enters the secondary heat exchanger 130 and is further cooledto nearly ambient temperature. The air exiting the secondary heatexchanger 130 then enters the water extractor 271, where any freemoisture is removed, to produce cool medium pressure air. This coolmedium pressure air then enters the turbine 214 through a nozzle. Thecool medium pressure air is expanded across the turbine 214 and workextracted from the cool high pressure air. Note that the chamberdischarge air exiting from the outflow valve heat exchanger 230 can thenbe sent to an outlet 202. The outlet 202 can be a cabin pressure controlsystem that utilized the energy of the chamber discharge air.

The two air flows (e.g., the fresh outside air sourcing from 201 and thebleed air sourcing from inlet 101) are mixed downstream of the turbine213 to produce mixed air. This downstream location can be considered afirst mixing point of the environmental control system 200. The mixedair leaves then enters the condenser 160 to cool the bleed air leavingthe primary heat exchanger 120. The mixed air is then sent to conditionthe chamber 102.

This low altitude operation can be consider a low altitude mode. The lowaltitude mode can be used for ground and low altitude flight conditions,such as ground idle, taxi, take-off, and hold conditions.

In high altitude operation of the environmental control system 200, thefresh outside air can be mixed downstream of the condenser 160 (ratherthan downstream of the turbine 113 or at the first mixing point). Inthis situation, the air exiting the water extractor 271 is the coolmedium pressure air. This cool medium pressure air is directed by thevalve V2 to downstream of the condenser 160. The location at which thiscool medium pressure air mixes with the bleed air, which is sourced fromthe inlet 101 and exiting the condenser 160, can be considered a secondmixing point of the environmental control system 200.

This high altitude operation can be considered a high altitude mode. Thehigh altitude mode can be used at high altitude cruise, climb, anddescent flight conditions. In the high altitude mode, fresh air aviationrequirements for passengers are met by mixing the two air flows (e.g.,the fresh outside air sourcing from 201 and the bleed air sourcing frominlet 101). Further, depending on an altitude of the aircraft, an amountof bleed air needed can be reduced. In this way, the environmentalcontrol system 200 provides bleed air reduction ranging from 40% to 75%to provide higher efficiencies with respect to engine fuel burn thancontemporary airplane air systems.

FIGS. 3, 4, and 5 illustrate variations of the environmental controlsystem 200. Turning now to FIG. 3, a schematic of an environmentalcontrol system 300 (e.g., an embodiment of the environmental controlsystem 200) is depicted according to an embodiment. Components of thesystems 100 and 200 that are similar to the environmental control system300 have been reused for ease of explanation, by using the sameidentifiers, and are not re-introduced. Alternative components of theenvironmental control system 300 include a compressing device 310, whichcomprises a compressor 312, a turbine 313, a turbine 314, and a shaft315, and a rotating device 316 (e.g., turbine driven fan), whichcomprises a turbine 317 and a fan 319, along with a secondary path forthe medium sourced from the inlet 101 (e.g., a valve V3 can provide themedium from the inlet 101 to an inlet of the turbine 317).

The environmental control system 300 operates similarly to theenvironmental control system 200 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 300 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 316. The turbine 317 of therotating device 316 is powered by the bleed air sourced from the inlet101 flowing through the valve V3.

Turning now to FIG. 4, a schematic of an environmental control system400 (e.g., an embodiment of the environmental control system 200) isdepicted according to an embodiment. Components of the systems 100, 200,and 300 that are similar to the environmental control system 400 havebeen reused for ease of explanation, by using the same identifiers, andare not re-introduced. Alternative components of the environmentalcontrol system 400 include a rotating device 416, which comprises amotor 417 and a fan 419.

The environmental control system 400 operates similarly to theenvironmental control system 200 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 400 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 416. The motor 417 of therotating device 416 is powered by electric power.

Turning now to FIG. 5, a schematic of an environmental control system500 (e.g., an embodiment of the environmental control system 200) isdepicted according to an embodiment. Components of the systems 100, 200,300, and 400 that are similar to the environmental control system 500have been reused for ease of explanation, by using the same identifiers,and are not re-introduced. Alternative components of the environmentalcontrol system 400 include a compressing device 510, which comprises acompressor 512, a turbine 513, and a shaft 515, and a rotating device516, which comprises a motor 517 and a fan 519. Note that the rotatingdevice 516 is along a path of the medium sourced from the inlet 201,such that the rotating device 516 can be supplied this medium orbypassed.

The environmental control system 500 operates similarly to theenvironmental control system 200 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 500 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 516. The turbine 517 of therotating device 516 is powered by the fresh air sourced from the inlet201.

Turning now to FIG. 6, a schematic of an environmental control system600 (e.g., an embodiment of system 100), as it could be installed on anaircraft is depicted according to an embodiment. In operation theenvironmental control system 600 can provide mixed air from anycombination of fresh air, bleed air, and cabin discharge air. Componentsof the systems 100, 200, 300, 400 and 500 that are similar to theenvironmental control system 600 have been reused for ease ofexplanation, by using the same identifiers, and are not re-introduced.Alternative components of the environmental control system 600 includean outlet 601 and a compressing device 610 that comprises a compressor612, a turbine 613, a turbine 614, a fan 616, and a shaft 618.Alternative components of the environmental control system 600 alsoinclude valves V6.1, V6.2, and V6.3. A path is further denoted by thedot-dashed line F6.1 for a flow the medium that is controlled by valveV6.1 to the outlet 601 (e.g., which can be overboard). Another path isdenoted by the dot-dashed line F6.2 for a flow the medium that iscontrolled by valve V6.2 for supplying the cabin discharge air to thevalve V6.3 (otherwise the cabin discharge air can be directed overboardthrough the shell 119). Note that the turbine 614 can be a dual use. Adual use turbine is configured to receive flows of different mediums inthe alternative.

In low altitude operation of the environmental control system 600,high-pressure high-temperature air from either the turbine engine or theauxiliary power unit via inlet 101 through the valve V1 enters theprimary heat exchanger 120. The primary heat exchanger 120 cools thepressure high-temperature air to nearly ambient temperature to producecool high pressure air. This cool high pressure air enters the condenser160, where it is further cooled by air from the turbines 613 and 614 ofthe compressing device 610. Upon exiting the condenser 160, the coolhigh pressure air enters the water extractor 272 so that moisture in theair is removed.

The cool high pressure air enters the turbine 613 through a nozzle. Thecool high pressure air is expanded across the turbine 613 and workextracted from the cool high pressure air. This extracted work drivesthe compressor 612 used to compress fresh outside air. This extractedwork also drives the fan 616, which is used to move air through theprimary heat exchanger 120 and the secondary heat exchanger 130.

The act of compressing the fresh outside air, heats the fresh outsideair. The compressed fresh outside air enters the outflow valve heatexchanger 230 and is cooled by the chamber discharge air to producecooled compressed fresh outside air. The cooled compressed fresh outsideair then enters the secondary heat exchanger 130 and is further cooledto nearly ambient temperature. The air exiting the secondary heatexchanger 130 then enters the water extractor 271, where any freemoisture is removed, to produce cool medium pressure air. This coolmedium pressure air then enters the turbine 614 through a nozzle. Thecool medium pressure air is expanded across the turbine 614 and workextracted from the cool high pressure air.

The two air flows (e.g., the fresh outside air sourcing from 201 and thebleed air sourcing from inlet 101) are mixed downstream of the turbine613 to produce mixed air. A valve V6.1 can then be used to direct anoutlet of the turbine 614 away from the chamber or to downstream of theturbine 613 (to provide the cool medium pressure air exiting the turbine614 to the first mixing point such that it flows to the chamber 102).This downstream location can be considered a first mixing point of theenvironmental control system 600. The mixed air leaves then enters thecondenser 160 to cool the bleed air leaving the primary heat exchanger120. The mixed air is then sent to condition the chamber 102.

This low altitude operation can be consider a low altitude mode. The lowaltitude mode can be used for ground and low altitude flight conditions,such as ground idle, taxi, take-off, and hold conditions.

In high altitude operation of the environmental control system 600, thefresh outside air can be mixed downstream of the condenser 160 (ratherthan at the first mixing point). In this situation, the air exiting thewater extractor 271 is the cool medium pressure air. This cool mediumpressure air is directed by the valve V6.3 to downstream of thecondenser 160.

The valve V6.3 can also direct the cabin discharge air to the turbine614. For instance, energy in the cabin discharge air can be used topower the compressor 612 by feeding (e.g., the dot-dashed line F6.2) thecabin discharge air to the turbine 614. Note that the cabin dischargeair enters the turbine 614 through a nozzle such that the turbine 614expands hot air from the outflow valve heat exchanger 230. The cabindischarge air can continue overboard (e.g., to outlet 601) through valveV6.1. Overboard comprise an ambient pressure at high altitude operation.By the cabin discharge air continuing to overboard, a pressure dropacross the turbine 614 is created such that the cabin discharge air isdrawn though the turbine 614 (e.g., cabin discharge air pressure ishigher than ambient air pressure). In this way, the compressor 612receives power from both the bleed air (across the turbine 613) and thecabin discharge air (across the turbine 614).

This high altitude operation can be considered a high altitude mode. Thehigh altitude mode can be used at high altitude cruise, climb, anddescent flight conditions. In the high altitude mode, fresh air aviationrequirements for passengers are met by mixing the two air flows (e.g.,the fresh outside air sourcing from 201 and the bleed air sourcing frominlet 101). Further, depending on an altitude of the aircraft, an amountof bleed air needed can be reduced. In this way, the environmentalcontrol system 200 provides bleed air reduction ranging from 40% to 60%to provide higher efficiencies with respect to engine fuel burn thancontemporary airplane air systems.

FIGS. 7, 8, and 9 illustrate variations of the environmental controlsystem 600. Turning now to FIG. 7, a schematic of an environmentalcontrol system 700 (e.g., an embodiment of the environmental controlsystem 600) is depicted according to an embodiment. Components of thesystems 100, 200, 300, 400, 500, and 600 that are similar to theenvironmental control system 700 have been reused for ease ofexplanation, by using the same identifiers, and are not re-introduced.Alternative components of the environmental control system 700 include acompressing device 710, which comprises a compressor 712, a turbine 713,a turbine 714, and a shaft 715. Note that the turbine 614 is a dual use.

The environmental control system 700 operates similarly to theenvironmental control system 600 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 700 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 316. The turbine 317 of therotating device 316 is powered by the bleed air sourced from the inlet101 flowing through the valve V3.

Further, energy in the fresh air exiting from the water extractor 271can be used to power the compressor 712 by feeding the air exiting thewater extractor 271 via the valve V6.3 to the turbine 714. Furthermore,energy in the cabin discharge air exiting from the outflow valve heatexchanger 230 can be used to power the compressor 712 by feeding (e.g.,the dot-dashed line F6.2) the cabin discharge air to the turbine 714. Inthis way, the additional or second turbine 714 can be fed air from theoutflow valve heat exchanger 230 (e.g., cabin discharge air) or airexiting the water extractor 271 (e.g., fresh outside air), while thefirst turbine 713 can be fed air from the primary heat exchanger 120(e.g., bleed air). In turn, the compressor 712 can receive power fromthe bleed air (via turbine 713), the cabin discharge air (via turbine714), and/or the fresh outside air (also via turbine 714). Note that thecabin discharge air or the fresh outside air can be mixed with the bleedair downstream of the turbine 713.

Turning now to FIG. 8, a schematic of an environmental control system800 (e.g., an embodiment of the environmental control system 600) isdepicted according to an embodiment. Components of the systems 100, 200,300, 400, 500, 600, and 700 that are similar to the environmentalcontrol system 800 have been reused for ease of explanation, by usingthe same identifiers, and are not re-introduced.

The environmental control system 800 operates similarly to theenvironmental control system 600 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 800 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 416. The motor 717 of therotating device 716 is powered by electric power.

Turning now to FIG. 9, a schematic of an environmental control system900 (e.g., an embodiment of the environmental control system 600) isdepicted according to an embodiment. Components of the systems 100, 200,300, 400, 500, 600, 700, and 800 that are similar to the environmentalcontrol system 900 have been reused for ease of explanation, by usingthe same identifiers, and are not re-introduced. Alternative componentsof the environmental control system 900 include a path for the mediumdenoted by the dot-dashed line F9 (where the medium can be provided fromthe chamber 102 to the turbine 714).

The environmental control system 900 operates similarly to theenvironmental control system 600 in that different mixing points areutilized based on the mode of operation. In addition, the environmentalcontrol system 900 separates the ram air fan (e.g., fan 116) from theair cycle machine (e.g., the compressing device 110) and provides theram air fan within the rotating device 516. The turbine 517 of therotating device 516 is powered by the fresh air sourced from the inlet201. Note that the rotating device 516 is along a path of the mediumsourced from the inlet 201, such that the rotating device 516 can besupplied this medium or bypassed based on the operation of valve V5. Inaddition, Note in one or more embodiments, an exhaust from the turbine714 can be sent to the outlet 202 (e.g., a cabin pressure controlsystem) after the turbine 714 extracts work from the medium receivedfrom path F9.

Aspects of the embodiments are described herein with reference toflowchart illustrations, schematics, and/or block diagrams of methods,apparatus, and/or systems according to embodiments. Further, thedescriptions of the various embodiments have been presented for purposesof illustration, but are not intended to be exhaustive or limited to theembodiments disclosed. Many modifications and variations will beapparent to those of ordinary skill in the art without departing fromthe scope and spirit of the described embodiments. The terminology usedherein was chosen to best explain the principles of the embodiments, thepractical application or technical improvement over technologies foundin the marketplace, or to enable others of ordinary skill in the art tounderstand the embodiments disclosed herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one more other features,integers, steps, operations, element components, and/or groups thereof.

The flow diagrams depicted herein are just one example. There may bemany variations to this diagram or the steps (or operations) describedtherein without departing from the spirit of embodiments herein. Forinstance, the steps may be performed in a differing order or steps maybe added, deleted or modified. All of these variations are considered apart of the claims.

While the preferred embodiment has been described, it will be understoodthat those skilled in the art, both now and in the future, may makevarious improvements and enhancements which fall within the scope of theclaims which follow. These claims should be construed to maintain theproper protection.

What is claimed is:
 1. An air cycle machine for an environmental controlsystem for an aircraft, the air cycle machine comprising: a compressorconfigured to compress a first medium; a turbine configured to receivesecond medium; a mixing point downstream of the compressor anddownstream of the turbine; a shaft mechanically coupling the compressorand the turbine; a second turbine mounted on the shaft and configured toexpand the first medium; and a fan driven by a motor.
 2. The air cyclemachine of claim 1, further comprising the fan on a second shaft.
 3. Theair cycle machine of claim 2, wherein the fan is located at a first endof the second shaft.
 4. The air cycle machine of claim 3, wherein athird turbine is located at a first end of the shaft.
 5. The air cyclemachine of claim 4, further comprising the fan located at a second endof the shaft.
 6. The air cycle machine of claim 3, wherein the secondturbine is configured to receive a third medium, and wherein the thirdmedium is cabin discharge air.
 7. The air cycle machine of claim 1,wherein the first medium comprises fresh air, and wherein the secondmedium comprises bleed air.
 8. An air conditioning system for anaircraft comprising: a compressor configured to compress a first medium;a turbine configured to receive a second medium; a mixing pointdownstream of the compressor and downstream of the turbine; and a shaftmechanically coupling the compressor and the turbine; a second turbinemounted on the shaft and configured to expand the first medium; and afan driven by a motor.
 9. The air conditioning system of claim 8,further comprising the fan on a second shaft.
 10. The air conditioningsystem of claim 9, wherein the fan is located at a first end of thesecond shaft.
 11. The air conditioning system of claim 10, wherein athird turbine is located at a first end of the shaft.
 12. The airconditioning system of claim 11, further comprising the fan located at asecond end of the shaft.
 13. The air conditioning system of claim 10,wherein the second turbine is configured to receive a third medium, andwherein the third medium is cabin discharge air.
 14. The airconditioning system of claim 8, wherein the first medium comprises freshair, and wherein the second medium comprises bleed air.